Circulating β chemokine and MMP 9 as markers of oxidative injury in extremely low birth weight infants

Matrix metalloproteinases (MMPs) and chemokines seem to be induced by hyperoxia in preclinical studies. We hypothesized that O2 exposure immediately after birth is associated with altered blood spot MMP 9 and β chemokine concentrations. The following analytes were measured on blood spots on d 1 and 3 of life, using luminex technology in 1059 infants (birth weights <1000 g) in the NICHD Neonatal Research Network: MMP 9, monocyte chemoattractant protein 1 (MCP 1), macrophage inflammatory proteins (1α and β), and regulated upon activation, normal t cell expressed and secreted (RANTES). Infants administered O2 continually from 6 to 24 h of life (n = 729), when compared with those with <6 h exposure (n = 330), had significantly lower mean birth weight and higher rate of respiratory distress syndrome (p < 0.002). On d 3, MCP 1 was higher and RANTES lower among infants with early prolonged O2 exposure. After adjusting for covariates, prolonged early O2 exposure retained a statistically significant association with higher MCP 1 on d 3 (p = 0.003). The consistent association between O2 exposure and MCP 1 among extremely preterm infants suggests that further investigation of its role in oxidative injury is warranted.